I. Field of the Invention
The present invention relates generally to conveyor systems and, more particularly, to a roller conveyor system.
II. Description of the Prior Art
There are many previously known roller conveyor systems having a frame with a pair of spaced apart rails. A plurality of roller assemblies are then rotatably mounted to the frame so that the roller assemblies extend transversely between the frame rails at spaced apart positions along the frame rails. These roller assemblies, furthermore, support the load or article which is to be conveyed by the roller conveyor system.
In many types of roller conveyor systems, the roller assemblies are powered, i.e. rotatably driven, by rotatably driving the roller assembly shafts. In some cases, the rollers are driven in unison with the shafts while in other cases, such as an accumulating roller conveyor system, the rollers are able to rotate relative to their mounting shafts.
In many of these previously known roller conveyor systems, a pair of bearing assemblies are employed for rotatably mounting the roller shaft to the frame rails with one bearing assembly mounted to each of the frame rails. These bearing assemblies typically include an inner race and an outer race which are rotatably mounted to each other by any conventional fashion, such as ball or needle bearings. The outer bearing race is typically secured to the conveyor frame by bolts or similar fasteners.
In order to minimize the frictional wear and tear between the roller assembly shafts and the bearing assemblies, the inner race of at least one, and typically both, bearing assemblies is secured to the roller shaft so that the roller shaft and inner bearing race rotate in unison with each other.
One previously known method of securing the roller shaft and inner race of the bearing assembly together has been to provide a drive pin extending through a diametric bore formed in both the bearing assembly inner race as well as the roller shaft. This previously known method, however, has several inherent disadvantages.
One disadvantage is that it is relatively expensive to machine the diametric opening through both the bearing inner race as well as the roller shaft. Such increased manufacturing cost necessarily increases the overall cost of the roller conveyor system, particularly since each roller conveyor system employs a large number of roller assemblies.
A still further disadvantage of this previously known method of securing the roller shaft to the bearing inner race has been that it is necessary that the openings in both the bearing inner race as well as the roller shaft precisely align with each other. Otherwise, it is not possible to position a drive bearing between the bearing inner race and the roller shaft. Such precision machining of both the roller shaft as well as the bearing inner race is necessarily expensive.
There have, however, been attempts to secure the bearing inner race to the roller shaft by machining a flat on the roller shaft which registers with the bearing inner race. A threaded fastener is then secured through a radially extending opening in the bearing inner race so that an inner end of the fastener abuts against the shaft flat upon tightening of the fastener. This previously known construction, however, has not proven effective in use.
A primarily disadvantage of this method of securing the bearing inner race to the roller shaft is that, after extended usage of the roller conveyor system, the threaded fasteners xe2x80x9cback outxe2x80x9d of their threaded holes in the bearing inner race. The attachment of the roller shaft to the bearing inner race becomes loose or, in some cases, the connection between the bearing inner race and the shaft is altogether lost. In either event, the frictional contact between the roller shaft and the bearing assemblies increases which can result in galling of the bearing assemblies and/or roller shafts and failure of the conveyor system.
A still further disadvantage of the previously known roller conveyor systems is that the rollers which support the article conveyed are fixedly secured to the roller conveyor shaft. Since different types of loads or articles require different placement of the rollers, it has been previously necessary to custom manufacture the roller assembly for each different roller conveyor system. This, in turn, unduly increases the overall cost of the roller conveyor system.
The present invention provides a roller conveyor system which overcomes all of the above-mentioned disadvantages of the previously known roller conveyor systems.
In brief, the roller conveyor system of the present invention comprises a frame having a pair of spaced apart rails. The roller conveyor system also includes at least one roller assembly, and more typically a plurality of roller assemblies, wherein each roller assembly includes an elongated shaft.
A pair of bearing assemblies are associated with each roller assembly with one bearing assembly being mounted to each rail so that the bearing assemblies in each pair are coaxially aligned with each other. Each bearing assembly, furthermore, includes both an inner and an outer race and in which the outer race is secured against rotation to the conveyor frame.
The elongated shaft of the roller assembly is then positioned through the inner races of the bearing assembly and the roller shaft includes a flat which is aligned with the inner race of at least one of the bearing assemblies.
A threaded fastener is threadably secured to the inner race of the bearing assembly. This fastener has one end adapted to abut against the shaft flat upon tightening of the fastener thereby securing the shaft to the inner bearing race. Furthermore, this fastener is dimensioned so that, with one end of the fastener in abutment with the shaft flat, the other end of the fastener is substantially flush with an outer surface of the bearing inner race.
A collar is then positioned over the outer surface of the bearing inner race. This collar has an inner diameter substantially the same as the outer diameter of the bearing inner race. Thus, with the collar positioned over the outer surface of the bearing inner race, the collar overlies the threaded fastener and prevents xe2x80x9cback outxe2x80x9d of the threaded fastener thus effectively locking the fastener against axial movement and maintaining the connection between the bearing inner race and the roller shaft.
At least one roller is secured to the roller shaft at a midpoint of the roller shaft so that the roller is positioned in between the frame rails. Preferably, the roller(s) is axially adjustably secured to the roller shaft by a pair of split rings with one split ring being positioned on each end of the roller.